One primary objective of this study is to delineate the vascular effects of prostaglandins (PGs), and intermediates in their biosynthesis, which may be important in the regulation of vascular smooth muscle contractility. Oxygenated products of arachidonic acid metabolism by lipoxygenase-like and PG synthetase enzyme systems will be isolated, and their activities on resistance and capacitance blood vessels will be studied in the intact animal and on isolated vascular smooth muscle preparations. High resolutions liquid chromatographic techniques will be employed for purification of the compounds and to determine the relative quantities of the compounds which may be released during neurogenic vasoconstriction and vasodilatiation in the canine cutaneous vascular bed. The vasoactivities of arachidonic acid and PGD2 and the possible interaction of the latter compound with PGE2- and PGF-2 alpha-induced vasomotor effects will also be investigated. The other major objective is to study mechanisms which may be involved in the action of PGs on vascular smooth muscle. The hypothesis that the actions of vasodilator PGs and vasoconstrictor PGs are associated with vascular cyclic AMP and cyclic GMP respectively will be tested. Vascular cyclic nucleotide phosphodiesterase activity in resistance vessels, and its possible alteration by PGs and imidazole will also be determined. The effect of cyclic endoperoxide PGs on vascular cyclic nucleotide generation will be determined, as well as these compounds' possible role in controlling the effects of oxygen on cellular cyclic GMP.